The respiratory rate is the rate at which

breathing Breathing (or ventilation) is the process of moving air into and from the lungs to facilitate gas exchange with the internal environment, mostly to flush out carbon dioxide and bring in oxygen. All aerobic creatures need oxygen for cellular ...

occurs; it is set and controlled by the

respiratory center The respiratory center is located in the medulla oblongata and pons, in the brainstem. The respiratory center is made up of three major respiratory groups of neurons, two in the medulla and one in the pons. In the medulla they are the dorsal ...

of the brain. A person's respiratory rate is usually measured in breaths per minute.

Measurement

The respiratory rate in

human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...

s is measured by counting the number of breaths for one minute through counting how many times the chest rises. A

fibre-optic An optical fiber, or optical fibre in Commonwealth English, is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means t ...

breath rate sensor can be used for monitoring patients during a

magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio wave ...

scan. Respiration rates may increase with

fever Fever, also referred to as pyrexia, is defined as having a body temperature, temperature above the human body temperature, normal range due to an increase in the body's temperature Human body temperature#Fever, set point. There is not a single ...

, illness, or other medical conditions. Inaccuracies in respiratory measurement have been reported in the literature. One study compared respiratory rate counted using a 90-second count period, to a full minute, and found significant differences in the rates.. Another study found that rapid respiratory rates in babies, counted using a stethoscope, were 60–80% higher than those counted from beside the cot without the aid of the stethoscope. Similar results are seen with animals when they are being handled and not being handled—the invasiveness of touch apparently is enough to make significant changes in breathing. Various other methods to measure respiratory rate are commonly used, including impedance pneumography, and

capnography Capnography is the monitoring of the concentration or partial pressure of carbon dioxide () in the respiratory gases. Its main development has been as a monitoring tool for use during anesthesia and intensive care. It is usually presented as a ...

which are commonly implemented in patient monitoring. In addition, novel techniques for automatically monitoring respiratory rate using wearable sensors are in development, such as estimation of respiratory rate from the electrocardiogram,

photoplethysmogram A photoplethysmogram (PPG) is an optically obtained plethysmogram that can be used to detect blood volume changes in the microvascular bed of tissue. A PPG is often obtained by using a pulse oximeter which illuminates the skin and measures cha ...

, or accelerometry signals. There are also modern applications that allow accurate respiratory rate measurement. Breathing rate is often interchanged with the term breathing frequency. However, this should not be considered the frequency of breathing because realistic breathing signal is composed of many frequencies.

Normal range

For humans, the typical respiratory rate for a healthy adult at rest is 12–15 breaths per minute. The

sets the quiet respiratory rhythm at around two seconds for an inhalation and three seconds exhalation. This gives the lower of the average rate at 12 breaths per minute. Average resting respiratory rates by age are: * birth to 6 weeks: 30–40 breaths per minute * 6 months: 25–40 breaths per minute * 3 years: 20–30 breaths per minute * 6 years: 18–25 breaths per minute * 10 years: 17–23 breaths per minute * Adults: 15–18 breaths per minute * 50 years: 18-25 breaths per minute * Elderly ≥ 65 years old: 12–28 breaths per minute. * Elderly ≥ 80 years old: 10-30 breaths per minute.

Minute volume

Respiratory minute volume Minute ventilation (or respiratory minute volume or minute volume) is the volume of gas inhaled (inhaled minute volume) or exhaled (exhaled minute volume) from a person's lungs per minute. It is an important parameter in respiratory medicine due ...

is the volume of air which is

inhaled Inhalation (or Inspiration) happens when air or other gases enter the lungs. Inhalation of air Inhalation of air, as part of the cycle of breathing, is a vital process for all human life. The process is autonomic (though there are exceptions ...

(inhaled minute volume) or exhaled (exhaled minute volume) from the

lung The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...

s in one minute.

Diagnostic value

The value of respiratory rate as an indicator of potential respiratory dysfunction has been investigated but findings suggest it is of limited value. One study found that only 33% of people presenting to an emergency department with an

oxygen saturation Oxygen saturation (symbol SO2) is a relative measure of the concentration of oxygen that is dissolved or carried in a given medium as a proportion of the maximal concentration that can be dissolved in that medium at the given temperature. It ca ...

below 90% had an increased respiratory rate. An evaluation of respiratory rate for the differentiation of the severity of illness in babies under 6 months found it not to be very useful. Approximately half of the babies had a respiratory rate above 50 breaths per minute, thereby questioning the value of having a "cut-off" at 50 breaths per minute as the indicator of serious respiratory illness. It has also been reported that factors such as

crying Crying is the dropping of tears (or welling of tears in the eyes) in response to an emotional state, or pain. Emotions that can lead to crying include sadness, anger, and even happiness. The act of crying has been defined as "a complex secr ...

sleep Sleep is a sedentary state of mind and body. It is characterized by altered consciousness, relatively inhibited sensory activity, reduced muscle activity and reduced interactions with surroundings. It is distinguished from wakefulness by a de ...

ing, agitation and age have a significant influence on the respiratory rate. As a result of these and similar studies the value of respiratory rate as an indicator of serious illness is limited. Nonetheless, respiratory rate is widely used to monitor the physiology of acutely-ill hospital patients. It is measured regularly to facilitate identification of changes in physiology along with other

vital signs Vital signs (also known as vitals) are a group of the four to six most crucial medical signs that indicate the status of the body's vital (life-sustaining) functions. These measurements are taken to help assess the general physical health of a ...

. This practice has been widely adopted as part of early warning systems.

Abnormal respiratory rates

References